Rectifier system.



F.'W. MEYER.

RECTIFIER SYSTEM.

APPLICATION FILED JUNE 20 19M.

1,291 ,066, Patented Jun.1'-1,191).

Iv x I WITNESSES:

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ATTORNEY errors.

FRIEDRICH W. MEYER, 0F PITTSBURGH, IEENNSYLVANIA, ASSIGNOR TO WESTING-HOUSE ELECTRIC A ND MANUFACTURING COMPANY, A CORPORATION OF PENN-SYLVANEA;

I To all euhom it may concern:

Be it known that 1,,FRIEDRICH W. lidurnn,

a subject of the Emperor of Germany, and a resident of Pittsburgh, inthe county of Allegheny and ,State of Pennsylvania, have 1nvented a newand useful Improvement in Rectifier Systems, of which the following is aspecification.

My invention relates tosystemsfor the conversion of energy fromalternating current to direct current, andniorespecifically to systemswherein energy is drawn from a a plurality of induction motors or likeappa ratus.

Referring to the form of my invention shown in Fig. 1, 3 is asingle-phase alternating current generator, operating at, for example,133 cycles and supplying energy to a system 4:. A three-phase generator5 oper-.

ating at, for example, cycles, supplies energy to a system 6 and atwo-phase gen'erator' 7 operating at, for example, 25 cycles, deliversenergy to a system 8.

It is desired to deriveenergy from all three of the circuits, l, 6 and 8and supply said energy to a common direct-current consumption circuit 9..In order toaccompli'sh this object, a rectifier 10, preferably of the40 vapor arc type, is provided with a plurality of anodes, in'this casenine being. employed, one of which is connected to a line wire in one ofthe systems. Anartificial neutral for the return of rectified current tothe system 4; is indicated at 11, one for the system 6 is indicated at12 and one-for the system 8 is indicated at13. The above'describedcircuit will operate satisfactorily if the voltages of the three systemsare such that all give'the' same rectified voltage. If, however, thevoltage of any one of the alternating current systems is such that itwill not give the re-- quired direct-current voltage, whe rectified,thedefect maybe easily remed e -by insertv Specification ofLetters-Patent.

RECTIFIER SYSTEM.

Patented Jan. ia, ieie.

Application filed June 20, 1914. Serial No. 846,364.

ing a transformer, having an adjustable ratio of transform'atiombetweenthe line wlres of the system in question and the respective anodes,'theartificial neutral for the return of the current from the direct-currentsystem beingtaken at the mid point of the secondary member or" thetransformer, as is well known in the art. Owing/to the wellknownopposition of the anodes of a vapor rectifier to the flow ofcurrent in a reverse direction, it is found that, in a system of thecharacter specified, there will be no disturbance of one of thealternating circuits by the others, but each will operate andtake theshare of the load determined by its voltage. If it is desired to controlthe amount of in energy delivered from each of the alternating-currentcircuits, suitable transformers may be inserted between the clrcuits tobe controlled and the rectifier and by adjusting the ratio oftransformation in these transformers, any desiredmlivisionof the loadmay be obtained.

Referring to the form of my invention shown in Fig. 2, it is well knownthat the torque of an induction motor, at a given 8o speed, isdetermined by the amount of energy induced in the secondary member bythe pri? mary member. The most common method of increasing the energyconsumption of a secondary member in order to obtain high torque at lowspeed, is the insertion of ohmic resistance in the secondary winding.While this is a commercially successfnl expedient during the shorttimewhen high induction is requiredv in the starting operation, it isJo highly inefficient when it is desired to operate an induction motor forlong intervals at a high slip, as is frequently the case in rollingmills and like places. Another common method of increasing the energyproduced in the secondarywinding is to connect said secondarywinding tothe. primary member of a second induction motor forming the well knowncascade connection. While thismethod of connection is commerciallyoperable where the hypo-synchronous speed to be obtained is an aliquotpart 0f synchronous speed, the method is not capable of applicationwhere great flexibility of speed control is desired, unless inefficientand wasteful ohmic resistance is inserted in thesecoiidary member of thesecond induction motor.

'I have found that, by passing the ourrent induced in the secondarymember of an induction motor through a rectifier, no matter what theSlip frequency of the machine may be, if proper voltage regulation isobtained by means of a transformer, current of uniform characteristics,that is to say, direct current, may be derived-from the rectifier.Furthermore, in accordance-with this invention, I have found that energyfrom a plurality of induction motor secondaries may be rectified in oneand the same rectifier, and said energy may be applied to adirect-current consumption circuit. Thus, for example, a large number ofinduction motors may be employed in a rolling mill and the secondaryenergy'from all of them may be conveyed to a central rectiably of thevapor-arc type. 22 is a second induction motor deriving alternatingcurrent for itsprimary member from the system 15 through leads 23 anddelivering energy from its secondary member through suitable slip rings241 and a transformer 25 having an adjustable ratio of transformation toanodes 26 in the rectifier 21. Rectified current from the cathode 27 ofthe rectifier 21 fiows through a direct-current consumption circuit,28,and thence back to they mid point of the transformers 19 and 25, 'as iswell known in the art.

A As was described in connection with Fig.1, alternating current fromthe secondary members of both induction motors will be rectified andsupplied to the circuit 28, and this method of connection may bemultiplied indefinitely,

controlling the speed of any desired number of induction motors bysuitable adjustment of the corresponding transformers. It may frequentlyhappen that there are not sulficient induction motors operating in aplant to supply the desired amount of energy to the direct-currentconsumption circuit 28. In order to provide for this contingency, Iprovide a transformer 29 which has an adjustable ratio of transformationand which may be connected directly to the system 15 by means of asuitable switch 30. The transformer 29 supplies energy to anodes .31 inthe rectifier 21 and, by suitable adjustment of the transformer 29, theamount of direct current supplied to the circuit 28 may be raised to anydesired amount, within the capacity of the'rectifier 21 and of thesupply system 15.

ency of It is desirablethat the direct-current system 28 be maintainedat constant potential ply thereto of an abnormal amount of energy from agiven unit at high voltage, the speed of every motor in the installationwould be at once changed. For satisfactory speed control, therefore, itis necessary that the .potential ofthe direct-current system be.maintained substantially constant, as by direct energy interchange withthe alternating current system, irrespective of the tendone or moremotors to produce alteration therein.

Having thus described my invention, what I claim is:

l. The combination with a'sourceof alternating current, of an inductionmotor having its primary winding connected thereto, a rectifying device,connections from the secondary winding of the induction motor to therectifying device, a direct-current consumption circuit supplied fromthe rectifying device, and means whereby energy desired in thedirectcurrent consumption circuit in excess of that derived from thesec- K ondary member of the induction motor may be derived from thealternating-current source.

2. The combination with a source of alternating current, of an inductionmotor having its primary winding connected thereto, a rectifying device,connections from the secondary winding of the induction motor to therectifying device, a direct-current consumption circuit supplied fromthe rectifying device, and connections from the alternating currentsource to the rectifying device, whereby energy desired in the directcurrent consumption circuit, in excess of that derived from thesecondary membefi of the induction motor, may be derived from thealternating-current source.

3. The combination with a source of alternating current, of an inductionmotor having its primary winding connected thereto, a vapor rectifier,connections from the secondary Winding of the induction motor to anodesof the vapor rectifier, connections from the source of alternatingcurrent to additional anodes in the vapor rectifier, and adirect-current consumption circuit connected between the rectifier andneutral points of said source and secondary circuits, respectively.

4. The combination with a plurality of inductionmotors, each of whichhas its pri-- mary winding connected to a source of alternating current,of a multi-anode vapor rectifier, connections including'volta'geadjusting means between the secondary winding of each induction motorand certain anodes in said rectifier, connections between a source ofalternating current of-definite frequency and certain other anodes insaid vapor rectifier, and a direct-current consumption circuit'connected between said vapor rectifier and neutral points of said sourceand secondary-circuits, respectively.

5. The combination with a source of alternating current,- of aninduction motor having its primary winding connected thereto, a vaporrectifier, an adjustable transformer connections fromthe secondarywind-ingot the induction motor to anodes of the apor rectifier throughvsaid adjustable transformenfconnections from the source of al ternatingcurrent to additional anodes in the vapor rectifier, and adirect-current constant potential consumptlon GlI'Olllt con-- nectedbetween the rectifier and neutral pointsvof'said source and secondarycircuit, respectively,whereby the electroinotive force across theterminals of the secondary member of the induction motofmay becontrolled. 1

. 6. The combination with a plurality of insupplied from the rectifier,whereby the electromotive force across the terminals of the secondarymember of the induction motors ma be controlled. v

n' testimony whereof, I have hereunto subscribed my name this 19thday-of June, 1914.-

a FRIEDRICH W. MEYER. i Witnesses: L

. D. G. Davis,

" B. B.'H1:Nr :s.

